I'm trying to horizontally align my UILable for iPhone screen, by there is no x or left in mylable properties.
How can center-align it on the screen?
The property you are looking for is the frame or center property. In this case, center is probably your best bet. All you need to do is something like this:
CGPoint newCenter = myLabel.center;
newCenter.x = self.view.center.x;
myLabel.center = newCenter;
or
myLabel.center = CGPointMake ( self.view.center.x, myLabel.center.y );
There are more advanced ways of maintaining center alignment using autolayout, or the autoresizingmask. If you are interested in learning about them (autolayout being the most robust and in some ways user friendly) I recommend watching the WWDC 2012 sessions about Auto Layout
The best way to determine what types of properties an object has is to use the class reference. When you first look at UILabel class reference you'll see there are no properties for adjusting the view of the label.
But if you look at the very top you can see where UILabel inherits from. You can see it inherits from UIView, which makes sense to look at for what you need since you're asking how to adjust the labels position on the screen (the view).
Click on UIView and you'll be taken directly to it's reference. Scroll down until you see a list of "Tasks" under which there are several categories, each with a number of properties. You're interested in the "Bounds and Frame Rectangles" category in which there is a property called "frame".
By now we've determined we can set the UILabels frame via myLabel.view.frame
But you may be wondering how to set a frame and so you need to click on 'frame' in the class reference you've been looking at.
You'll see that frame is of type CGRect, so you can use CGRectMake to set the frame. But now you're asking how do I do that, so we click on the CGRect reference.
And you can see that CGRect is a struct made of a CGPoint and a CGSize and if necessary please look those up as well to understand how they are defined.
I took this time to explain the flow of using the docs so that you can do it for yourself in the future. You can survive for awhile on the help of others, but eventually you'll need to just dive into the docs and figure it out for yourself.
In short, you can set the position of your label using the following:
myLabel.frame = CGRectMake(self.view.frame.size.width/2-someWidth/2, self.view.frame.size.height/2-someHeight/2, someWidth, someHeight);
Where someWidth and someHeight are custom variables of float type and self.view is some superview you want to center the label in.
I did not test the code but believe this should work. Good luck to you.
This works:
mylabel.center = CGPointMake(CGRectGetMidX(self.view.bounds), mylabel.center.y);
Related
I have an app which allows users to send messages to each. The process is accomplished by saving the sent messages in a local SQLite database, while actually sending the messages to a database and using push notifications to send the message to the recipient's SQLite database. The set up I have works fine. However, what I am confused about is how to set up the actual interactive UI for the user (I am using XCode). I figured it should be a UITableView with each table cell representing a message. However, with this approach I run into a few requirements:
Variable TextView Sizes
Just as with regular iOS messaging, the TextView's size needs to be variable, adjusting its dimensions to fit all of the text in each message. I do not know how to accomplish this. I have a general understanding of how to generally vary sizes, but no clue how to dynamically have it based on the text within that view.
Variable TextView Positions
Again, just as with regular iOS messaging, the textview needs to be offset to either the right or left side depending on whether the sender was the user or who the are conversing with, respectively. I also do not know how to do this, because it changes the center of the textview.
Non-selectability
Xcode allows cells to be pressed. Handling what happens after this selection can be achieved by the didSelectRowatIndexPath tableView function. I can simply not implement this, but clicking on the cell causes it to turn darker to indicate it has been pressed. I would like to eliminate this while retaining the ability to, say, select some of the text and copy and paste it or whatever (just like messaging works normally on your phone).
Other Approaches?
This is the real meat of the question. I have considered the above approach because that is all that I have been able to come up with based on my limited experience with XCode UI elements. If there is a better approach (perhaps even a pod or framework) for this purpose I would love to hear it. I do not need the messaging UI to look amazing, just clean and crisp.
I suggest the following:
Variable TextView Sizes:
I assume you do use auto layout. If you don’t yet, please consider using it since it make life much easier!
If you use a UITableView, you can adjust the height of its UITableViewCells dynamically, depending on the actual content by using self-sizing cells. You can find a tutorial how to do this here.
Variable TextView Positions:
I assume you have a UITextView within a table view cell. In this case, you have to set auto layout constraints to the borders of the cell’s contentView. If you define a custom subclass of a UITableViewCell, you can define in this class 2 IBOutlet properties that are linked to say the left and the right layout constraints (e.g. var leftLayoutConstraint: NSLayoutConstraint). Then, you can set the constraint’s constant property as required when the cell is laid out, i.e. in the layoutSubviews function of the custom table view cell.
Non-selectability:
I am not sure what you mean by „I can simply not implement this“. Please make sure that you set the delegate property of the UITableView to the view controller where you want to handle cell selection. Selecting a cell changes the cells color by default, but you can change this: In the storyboard, select your table view’s prototype cell, and open Xcode’s utility pane (top rightmost button). Under „Table view cell“ you find „Selection“ that you can set to „None“.
I hope this helps!
I've built a custom control in Cocoa which is drawn using an NSBezierPath and I'd like it to change shape when it's state has changed (unused state = a pointed 'look here' edge, used state = standard control edge).
It feels like I've looked through every mention of "NSBezierPath" and "Animation" there is on the web but with no luck.
Before I crack out some NSTimers and write my own timing & path point controls, does anyone know if this is possible using Core Animation or similar?
You could use NSAnimation. Create your own NSAnimation subclass, and override setCurrentProgress method.
In that method, you can change your NSBezierPath size, shape or whatever you need, based on current animation progress. After that you can force a redraw in the view (via delegate, for instance) to re-display the path.
I'm relatively new to Cocoa programming, but I've managed to figure a fair amount out. One thing I haven't been able to figure out yet is how to have an element that is visible over all views. Like a volume control that is always visible just above the tab bar at the bottom of the screen.
How should I go about doing that?
If you just need to bring a view to the front, you can use bringSubviewToFront:, like so:
[self.view bringSubviewToFront:yourSubview];
If you need to position subviews so that they overlap in a certain way, you'll want to make use of CALayer. Just be aware that overlapping UIControl elements goes against Apple's Human Interface guidelines.
When writing Cocoa apps, I do the majority of the user interface layout programmatically. For example:
NSRect popUpFrame = NSMakeRect(10, 10, 100, kDefaultPopUpButtonHeight);
NSPopUpButton * popUp = [[NSPopUpButton alloc] initWithFrame:popUpFrame];
//...
My question is about that kDefaultPopUpButtonHeight constant. I currently maintain a source file full of such constants, and I fill in the proper sizes manually. I am able to determine the correct sizes by dropping a new control into a blank view in Interface Builder and then checking its properties to see what size IB gives it.
There must be a better way. Is it possible to access these values at runtime? Ideally, I would expect every NSControl to have a class method something like: +(NSSize)defaultSize, or, for controls like NSButton that have different default sizes depending on the particular button style used, something like +(NSSize)defaultSizeForButtonStyle:(NSButtonStyle)buttonStyle.
Apple's Human Interface Guidelines has information about control layout and the spacing between controls, but it doesn't say anything about the proper sizes for individual controls.
I agree with Peter, and would recomend that you use Interface Builder. But if that isn't appropriate in your situation, here's one way to find the best size for most controls:
NSSize idealSize = [[control cell] cellSize];
If you need more control over the sizing, you can use the -[NSCell cellSizeForBounds:] method.
Also, cellSize really gives you the minimum size for a control, not necessarily the best size. For example, for a Cocoa aqua style push button with the text "OK", it would return a width that more narrow than the HIG would recommend. For your purposes, it sounds like you're only interested in the fixed hight portion of the size. -[NSCell cellSize] should work great.
Is there a simple way to create a selectable NSRect in Cocoa? In need a rectangle that can be selected and stays selected after a mouse click.
Thanks.
NSRect is just a struct with a position and size. It's not an object that can actually do anything or have any properties other than a width and height. It sounds like what you want is to create an NSView that can be selected. (Here's Apple's Guide on the subject.)
Though not as immediate as you would like, you may be interested in the management of tracking rectangles and tracking areas performed by NSView class.
This mechanism allows you to define specific areas of your custom view. Then, an event is generated whenever the cursor enters or leaves the area, or a mouse button is pressed in this area (-mouseEntered:, -mouseExited:, -mouseDown:, -mouseUp:, -mouseDragged:, ... of NSResponder class). This up to you to define what you want your application do in response to these events (set the rectangle as selected and display it accordingly).
For an example implementation of this, take a look at the Sketch example included with the Apple developer tools (look in /Developer/Examples/AppKit). Sketch allows the user to create new graphics (including rectangles, but also ovals, lines, and text), select them, move them around in the document, etc. In particular, you'll probably want to look at the SKTGraphic class, which represents a single graphic object in the document, and the SKTGraphicView class, which is an NSView subclass that perform the actual layout and drawing, handling mouse events for dragging views around, etc.